1. Field of the Invention
The present invention relates to a novel solution of sodium hypochlorite, namely a stable solution of this product which is suitable as an antiseptic.
2. Prior Art
Sodium hypochlorite solution has been used for its bactericidal properties since the beginning of the 19th century (in particular since the work of LABARRAQUE in about 1820). In 1914, for use in the washing of war wounds, DAKIN found it necessary to neutralize the excess alkalinity of the solution in order to reduce its irritant action. For this neutralization, he used boric acid at a rate of about 4 g per liter. DAUFRESNE subsequently replaced the boric acid with sodium bicarbonate, but it is the so-called VAL de GRACE formulation published in about 1930 which was entered in the pharmacopeia under the name of DAKIN's solution.
Neutral dilute sodium hypochlorite solution (DAKIN's solution) is entered in the French Pharmacopeia, 10th edition, January 1989, under the following formulation:
monosodium carbonate: 15 g PA0 Javelle water, in a quantity sufficient to yeild: 5 g of active chlorine PA0 potassium permanganate: 0.01 g PA0 cold boiled water in a quantity sufficient to yield a 1000 ml solution PA0 sodium hypochlorite in a quantity sufficient to yield 5 g of active chlorine PA0 monosodium phosphate in a quantity sufficient to yield a pH of 9.6 to 10 PA0 purified water in a quantity sufficient to yield a 1 liter solution
As sodium hypochlorite decomposes rapidly to release chlorine, it is specified in said pharmacopeia that this solution must be stored for a maximum of fifteen days in stoppered containers, in a cool place at a temperature below 15.degree. C. and protected from the light. The lower limit of active chlorine accepted for the solution is 4 g of active chlorine per liter.
A time limit as short as this makes it very difficult to utilize this product industrially.
Through the development of very particular manufacturing conditions, excluding especially the presence of metal particles, it has been possible to obtain a solution with a time limit corresponding to D+14, D being the day of acceptance by the control services [q.v. Ann. Pharmaceutiques Francaises 1984, 42, No. 5, pp. 417-423].
In his thesis presented to the Faculty of Pharmacy in Dijon on Feb. 16, 1987, J. F. LAHET concluded that the instability of DAKIN's solution at room temperature is a reality and still limits its use.
In patent FR 2 593 704, the Applicant described a dilute solution of sodium hypochlorite stabilized with monosodium phosphate, which has the following composition:
The monosodium phosphate must be used in a sufficient amount to give the sodium hypochlorite solution a pH of between 9.6 and 10 and preferably of between 9.7 and 9.9. This pH range makes it possible to achieve a stability of about six months or more.
This hypochlorite solution can also contain any type of coloring substance which is inert towards the hypochlorite and the monosodium phosphate. This substance can advantageously be potassium permanganate, as in DAKIN's solution.
However, it has proved necessary to continue researching in order to obtain a sodium hypochlorite solution with a longer storage time.